One of the most important methods of disseminating plant protecting agents is by spraying of aqueous plant protecting solutions with the aid of a spraying device. Different types of spraying devices are known, from which the substance to be sprayed is discharged by means of a hand-operated or motor-driven pump. The spray liquor is prepared separately shortly before dissemination by diluting a concentrated active substance with water or other suitable liquid. A major disadvantage of this process is the fact that the user comes into contact with the concentrated active substance when mixing the spray liquor. In addition, wrong dosages may easily be used and frequently more substance is applied than is necessary and sensible in order to protect the plant. Furthermore, there are problems with the elimination of the left-over plant protecting agent and with storing any unused concentrated plant preservative.
The disadvantages described above are encountered particularly by small-scale users who employ the sprays in the house and garden, since such people often require only very small quantities of plant protecting agent but, as a result of the variety of the plants they cultivate, they keep a large number of plant treatment compositions having different activities on hand. Thus, the small-scale user must always ensure that opened packages of concentrated active substances are properly stored.
Modern plant treatment compositions have been developed to such an extent that only tiny quantities of active substance are required to achieve the desired results. When plant treatment compositions are used on a small scale, only tiny volumes of the solvent concentrate are required in order to produce the small quantities of spray liquor required, such as 0.5 to 10 liters. It is very difficult to measure these quantities of concentrate, which are frequently less than 1 ml per liter of spray liquor.
Errors in measurement, leading to overdosing and underdosing, are therefore frequent. Dilution of the solvent concentrate would indeed improve accuracy of measurement, but the disadvantage is that more excipients and solvents are used than are necessary to provide the plant protection sought. Furthermore, dilute solutions are less stable than concentrated solutions.
Spray-Liquors are also frequently of the wrong strength since many users have difficulty calculating the dosage of concentrated active substance corresponding to the capacity of the pressure spray from the concentrations recommended by the manufacturer.
Ready-to-use aqueous solutions of plant protecting agent diluted to the proper concentration for use, packed in bottles with pump atomizers, are now also available. These eliminate the risk of wrong dosages, and the user does not come into contact with the concentrated active substance. However, the storage stability of such aqueous formulations is generally unsatisfactory. Moreover, the costs of storage and transport of bottles of this kind are high since the solutions as a rule contain more than 99% water.
To solve the problem life and accuracy of dosing, German Auslegsschrift No. 1,939,086 discloses a container for storage and preparation of a spray liquor of plant protecting agent:
A plurality of cups or beakers in which the concentrate is stored separately from the diluent are inserted into a bottle containing the diluent. When a hand pump is fitted on the bottle, the feed pipe of the pump penetrates the bases of the cups from the outside inwards.
After the hand pump has been tightly sealed, the concentrate can be mixed with the diluent and then sprayed using the hand pump.
This apparatus solves the problem of inadquate storage stability since the active substance and diluent are separated from each other until the moment of use. However, the following points, which may be summarized as follows, remain unsolved.
The cups of concentrate are opened from the outside inwards. There is a risk of undiluted concentrate running out. PA1 The feed pipe passes through the individual cup bases only to an extent which is limited by the radius of the feed pipe. For this reason, and because the feed pipe remains in the opening, the diluent and concentrate can only be partially mixed together, particularly if the concentrate has a fairly high viscosity. PA1 Owing to the fact that the function of the feed pipe is to penetrate the cup base, it must be very rigid and cannot be flexible. This means that the dilution prepared cannot be completely removed from the container by spraying. A residual amount of dilution is left behind.
Considered in terms of the overall structure of the system, this device can only be sensibly used if the diluent and concentrate are sold packed together in a bottle.
Consequently, the above-mentioned problems of high storage and transport costs are not solved.
Heretofore, there has been no entirely satisfactory re-usable device for disseminating spray liquors of plant protecting agents which combines the aspects of maximum possible safety of use, good storage stability, low storage and transport costs and good miscibility of concentrate and diluent.